my boyfriend doesn't believe I cum

I've been with my boyfriend for about 3 years.  The sex has always been fantastic.  I get off from clitoral stimulation, not penetration, so usually after my boyfriend gets off, then he fingers me til I cum.  The last few months he has said that my reation after I cum is different than normal, and that he doesn;t believe I actually cum.  He says that women can fake it and get away with it.  The thing is I have never actually faked an orgasm, and I do not plan to start.  So the first couple times he said this, I told him that I wasn't faking, and that sometimes I just feel more energized afterwards instead of feeling tired.  However, it did make me a little insecure.  I tried not to read too much into it, but he keeps saying it now.  And he doesn't ever believe me when I tell him that I really did get off.  The frist few times he said he did believe me after we talked about it.  Now he does not.  It's gotten so that I feel uncomfortable even getting undressed because I don't want to have sex.  I just want to avoid the akward time after.  I used to feel good after we had sex, and the last time I did, until he said that he thought I faked it, and then I just felt bad.  I am not even sure how to name the feeling, just akward and insecure, and like I wanted to never be naked again.  I take the intimacy we have seriously, and I have never been intimate like this with anyone else.  For the record, I almost always tell him how good it was or complement him because it I like it so much.  I want to go back to having sex and it being good afterwards.  And I want to feel that it is worth sharing this part of myself with him.  What do I do?